US3714123A - Process for making ethylene polymers or copolymers in a pressure-pulsed tubular reactor - Google Patents

Process for making ethylene polymers or copolymers in a pressure-pulsed tubular reactor Download PDF

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Publication number
US3714123A
US3714123A US00095743A US3714123DA US3714123A US 3714123 A US3714123 A US 3714123A US 00095743 A US00095743 A US 00095743A US 3714123D A US3714123D A US 3714123DA US 3714123 A US3714123 A US 3714123A
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peroxide
reactor
process according
section
mols
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US00095743A
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English (en)
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C Mancini
R Gaspari
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Societa Italiana Resine SpA SIR
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Societa Italiana Resine SpA SIR
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J19/24—Stationary reactors without moving elements inside
    • B01J19/2415—Tubular reactors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J3/00—Processes of utilising sub-atmospheric or super-atmospheric pressure to effect chemical or physical change of matter; Apparatus therefor
    • B01J3/04—Pressure vessels, e.g. autoclaves
    • B01J3/042—Pressure vessels, e.g. autoclaves in the form of a tube
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F10/00—Homopolymers and copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00049—Controlling or regulating processes
    • B01J2219/00051—Controlling the temperature
    • B01J2219/00054—Controlling or regulating the heat exchange system
    • B01J2219/00056—Controlling or regulating the heat exchange system involving measured parameters
    • B01J2219/00065—Pressure measurement
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00049—Controlling or regulating processes
    • B01J2219/00051—Controlling the temperature
    • B01J2219/00074—Controlling the temperature by indirect heating or cooling employing heat exchange fluids
    • B01J2219/00087—Controlling the temperature by indirect heating or cooling employing heat exchange fluids with heat exchange elements outside the reactor
    • B01J2219/00094—Jackets

Definitions

  • the present invention relates to the manufacture of polyethylenes, or copolymers of ethylene with other polymerizable monomers, using the high pressure technique, and more precisely it relates to the controlling of the pressure in the tubular reactors, i.e. reactors with a high ratio of length to diameter.
  • reaction initiators consisting of substances capable of generating free radicals in the conditions under which polymerization is performed.
  • peroxides are used as initiators and can be supplied at several points along the body of the tubular reactor.
  • the thermal effect of the reaction is also controlled by heat exchanger fluids situated outside the tubular reactor,
  • Such impulses are normally obtained by the total and rapid opening and closing of exit valves from the reactor at predetermined intervals of time.
  • the pattern of pressure in the reactor as a function of time thus becomes typically sawtooth with rapid pulsations of pressure between maximum and minimum values. More particularly and referring to the attached FIG. 1, it is possible to have a simple sawtooth pattern with the'pressure variable continuously between the maximum value P and minimum value P or it is possible to have the pattern shown in FIG. 2 in which, between one complete opening of the valve and the next, there is a more or'less prolonged period during which the pressure is maintained virtually constant at its maximum value P This mode of operation is however not without its drawbacks.
  • reaction initiators norm ally in the form of solutions in organic solvent
  • the process of the present invention is based substantially on the fact that uncontrolled reaction conditions are avoided when, in pulsation, the return of the pressure from its minimum to its maximum levels takes place relatively slowly.
  • Periodically superimposed, on the continuous discharge is an intermittent discharge through a second cross-section by the rapid opening and closing of the discharge valve.
  • the rapid opening and closing of the discharge valve is intended to mean that these operations take place in times of the-order of a few tenths of a second.
  • the position of the valve at the end of the reactor at which the products of reaction are discharged is varied to a position of total opening and one of partial opening and vice versa. In other words, it is no longer necessary for the valve to have to close completely at any time.
  • the conditions of minimum opening may be achieved by appropriate shaping of the discharge valve; it is also possible to make two independent discharges, one of which is continuous while the other is intermittent.
  • the ethylene is supplied continuously to one end of a tubular reactor capable of withstanding pressure and having a ratio of length:diameter of 100:1 to 100,000: 1.
  • Compounds having a terminal vinyl unsaturated group may be used as copolymerizable monomers. Examples which may be cited are: acrylic and methacrylic acids and their derivatives such as the esters of acrylic and methacrylic acids, for example the methyl, ethyl and stearyl esters. Other useful comonomers are vinyl chloride and vinylidine chloride and the vinyl carboxylates such as vinyl acetate and vinyl propionate.
  • Such comonomers are used up to a maximum quantity equal to approx. 35 mols per 100 mols of ethylene.
  • Polymerization is carried out at temperatures between 100 and 350 C and at pressures between 1,000 and 4,000 kg/sq.cm.
  • Useful initiators of copolymerization are those organic compounds which produce free radicals under conditions of reaction and preferably organic peroxides which, normally dissolved in organic solvents, are supplied at one or preferably more points along the tubular reactor.
  • organic peroxides 2,4 -dichlorobenzoyl peroxide, propionyl peroxide, caproyl peroxide, octanoyl' peroxide, caprylyl peroxide, pelargonyl peroxide, isononanoyl peroxide, decanoyl peroxide, lauroyl peroxide, benzoyl peroxide, isopropyl peroxide-carbonate, tertiary butyl peracetate, tertiary butyl hydro-peroxide, tertiary butyl periso-octoate, dicumyl peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide, cumene hydroperoxide, ditertiary butyl peroxide and p-menthane hydroperoxide.
  • Such hydroperoxides are supplied in quantities of 5 to 500 mols per mols of polymerizable monomer.
  • the solvents for the initiators useful for the purposes of the present invention, are the normally liquid aliphatic hydrocarbons such as hexane, heptane and cyclohexane, or the aromatic hydrocarbons such as benzene and toluene. It is also possible to use mixtures of aromatic hydrocarbons and aliphatic hydrocarbons.
  • chain transferers may be present, consisting for example of saturated aliphatic hydrocarbons such as: propane, butane, isobutane, pentane, hexane and heptane; alicyclic hydro-carbons such as cyclohexane, methyl cyclohexane, cyclopentane; aromatic hydrocarbons or chlorinated hydrocarbons.
  • saturated aliphatic alcohols containing from one to six or more carbon atoms on the molecule may be used as chain transferers, particularly the primary and secondary alcohols such as for example: methanol, ethanol, propanol, n-butanol, pentanol, hexanol, isopropanol, isobutanol and secondary butanol.
  • These compounds are used in quantities of 0.2 to 6 mols per 100 mols of polymerizable monomer.
  • chain transferers in the molar quantities quoted, aliphatic ketones such as for example acetone, diethyl ketone, diisobutyl ketone, methyl ethyl ketone, methyl isopropyl ketone and ethyl butyl ketone.
  • aldehydes such as for example: formaldehyde, acetaldehyde and n-valeraldehyde in quantities of 0.05 to 3 mols per mols of polymerizable monomer.
  • unsaturated hydrocarbons such as: propylene, butene-l butene-2, hexene-l 3-methyl butene, octene-l, monene-l, decene-l, undecene-l and dodecene-l may be used as chain transferers and partial comonomers. Normally, such compounds are used in quantities of 0.1 to 4 mols for every 100 mols of polymerizable monomer.
  • a fundamental aspect of the process of the present invention is the fact that the products are expelled by a pulsating discharge which is superimposed on a continuous discharge at the end of the reactor in which the products of reaction are discharged.
  • the pulsations are obtained by the rapid opening and closing of the discharge valve in the intermittent discharge section, controlling, by means of measures well known in the art, the effects of the irregular fluctuations in pressure due to various causes, so as to obtain pulsations of desired frequency and amplitude.
  • the difference between the maximum pressure and minimum pressure of pulsations is desirably of the order of 100 to 500 kg/sq.cm. measured at the end of the reactor in which the ethylene is supplied, and preferably to 450 kg/sq.cm., the cross-section of continuous discharge being at 5 to 30 percent and preferably 5 to 15 percent of the total maximum discharge cross-section provided when the intermittent discharge is superimposed.
  • the pattern of pressures over a period of time thus assumes the aspect represented in FIGS. 3 or 4.
  • EXAMPLE 1 Ethylene polymerization was carried out in a pressure resistant tube having an inside diameter equal to 32 mm and a length equal to more than 700 m.
  • the tube was jacketed so that the thermal effects of reaction could be controlled by means of heat exchanger fluids.
  • the apparatus also comprised means for introducing ethylene and catalytic mixture.
  • the ethylene was supplied completely at one end of the tubular reactor in quantities equal to approx. 17,000 kg/hr. while the catalytic mixture was supplied at two points situated respectively at a distance equal to 20 percent and 45 percent along the body of the reactor calculated from the end at which the ethylene was supplied.
  • the catalytic mixture used was a toluene solution of decanoyl peroxide and ditertiary butyl peroxide; these peroxides were supplied in quantities equal to 35 mols per mols of ethylene.
  • the pressure used was 2,450 kg/sq.cm., the temperature being 60 C at the point of ethylene intake, reaching 180 C at the first supply of intiator solution, after which the temperature reached two maxima respectively equal to 320 C and 305 C.
  • the temperature was regulated by means of pressurized water which was caused to circulate in the jacket enclosing the tubular reactor.
  • the chain transferer used was propylene supplied by vacuum to the secondary compressor and in quantities equal to 0.9 mols per 100 mols of ethylene.
  • a pulsating pressure was achieved by causing the reactor discharge valve to fluctuate from the position of total opening to a position of opening equal to 5 percent in respect of total opening.
  • EXAMPLE 2 (COMPARATIVE) A procedure was adopted as in Example 1, but eliminating the continuous discharge and causing the discharge valve to pulse between the position of total opening and that of total closure 1 1 times per minute.
  • a process for the manufacture of polyethylene or copolymers of ethylene containing up to 35 mol percent of other polymerizable monomers by supplying monomers to one end of a tubular reactor having a proportion of lengthzdiameter of 100:1 to 100,000:l and proceeding at temperatures from 100 to 350 C, with pulsating pressures and at values comprised between 1,000 and 4,000 kg/sq.cm., and in the presence of peroxide initiators said initiators being laterally introduced as side streams in an organic solvent into said reactor through one or more positions on the reactor, at least one of said positions not being at said end,
  • the contents in the reactor, at the end at which the products of reaction are recovered, are discharged partly continuously through a discharge cross-section maintained constant over a period of time and partly intermittently through a rapidly opened and closed second discharge cross-section.
  • the said peroxides are chosen from
  • a process according to claim 1 characterized in that compounds with an unsaturated terminal vinyl group are used as comonomers for the ethylene.
  • a process according to claim 1 characterized in that to the polymerization reactor are supplied chain transferers consisting of aliphatic hydrocarbons, aliphatic alcohols or aliphatic ketones in quantities of 0.2 to 6 mols per 100 mols of polymerizable monomers, or aldehydes in quantities of 0.05 to 3 mols per 100 mols of polymerizable monomers.
  • a process for the manufacture of polyethylene of copolymers of ethylene containing up to 35 mol. percent of other polymerizable monomers by supplying monomers to one end of a tubular reactor having a proportion of length2diameter of 100:1 to 100,000:l and proceeding at temperatures from 100 to 350 C, with pulsating pressures and at values comprised between 1,000 and 4,000 kg/sq.cm., and in the presence of peroxide initiators, being laterally introduced as side streams in an organic solvent into said reactor through one or more positions on the reactor, at least one of said positions not being at said end, characterized in that the contents in the reactor at the end which the products of the reaction are recovered, are discharged partly continuously through a continuous discharge cross-section maintained constant over a period of time and partly intermittently through an intermittent discharge rapidly opened and closed second discharge cross-section, said continuous discharge cross-section being maintained at 5 to 30 percent of the total maximum cross-section of discharge which is provided when the intermittent discharge is superimposed, with a frequency of opening and closing of said second discharge

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
  • Polymerisation Methods In General (AREA)
US00095743A 1969-12-23 1970-12-07 Process for making ethylene polymers or copolymers in a pressure-pulsed tubular reactor Expired - Lifetime US3714123A (en)

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Application Number Priority Date Filing Date Title
IT2620169 1969-12-23
US9574370A 1970-12-07 1970-12-07

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US (1) US3714123A (de)
CH (1) CH529797A (de)
DE (1) DE2063190A1 (de)
FR (1) FR2074055A5 (de)
GB (1) GB1282237A (de)
NL (1) NL7018035A (de)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3875128A (en) * 1973-05-04 1975-04-01 Sumitomo Chemical Co Process and apparatus for producing ethylene polymer
US4046718A (en) * 1976-06-17 1977-09-06 The Dow Chemical Company Polymerization method employing tubular reactor
US4169929A (en) * 1977-05-16 1979-10-02 Basf Aktiengesellschaft Manufacture of low density ethylene polymers of improved homogeneity
US4332924A (en) * 1978-07-05 1982-06-01 The Dow Chemical Company Recirculating polymerization method and apparatus with evaporative cooling
US5057593A (en) * 1990-06-11 1991-10-15 E. I. Du Pont De Nemours And Company Free radical copolymerization of ethylene and CO with acetone
WO2007134671A1 (en) * 2006-05-19 2007-11-29 Exxonmobil Chemical Patents Inc. A process for the production of polyethylene copolymers
US8445606B2 (en) 2008-12-18 2013-05-21 Exxonmobil Chemical Patents Inc. High pressure polymerization process
US10358511B2 (en) 2009-12-22 2019-07-23 Exxonmobil Chemical Patents Inc. Separation vessels for use in polymerization processes and methods for cleaning same

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2852501A (en) * 1954-10-05 1958-09-16 Monsanto Chemicals Polymerization of ethylene
CA573362A (en) * 1959-03-31 E. Guillet James High density polyethylene by high pressure polymerization with small amounts of aldehydes
US3294773A (en) * 1965-08-12 1966-12-27 Halcon International Inc Control scheme for polyethylene reactor
US3334081A (en) * 1960-08-29 1967-08-01 Union Carbide Corp Polymerization process
US3373148A (en) * 1961-07-21 1968-03-12 Monsanto Co Polymerization of ethylene

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA573362A (en) * 1959-03-31 E. Guillet James High density polyethylene by high pressure polymerization with small amounts of aldehydes
US2852501A (en) * 1954-10-05 1958-09-16 Monsanto Chemicals Polymerization of ethylene
US3334081A (en) * 1960-08-29 1967-08-01 Union Carbide Corp Polymerization process
US3373148A (en) * 1961-07-21 1968-03-12 Monsanto Co Polymerization of ethylene
US3294773A (en) * 1965-08-12 1966-12-27 Halcon International Inc Control scheme for polyethylene reactor

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3875128A (en) * 1973-05-04 1975-04-01 Sumitomo Chemical Co Process and apparatus for producing ethylene polymer
US4046718A (en) * 1976-06-17 1977-09-06 The Dow Chemical Company Polymerization method employing tubular reactor
US4169929A (en) * 1977-05-16 1979-10-02 Basf Aktiengesellschaft Manufacture of low density ethylene polymers of improved homogeneity
US4332924A (en) * 1978-07-05 1982-06-01 The Dow Chemical Company Recirculating polymerization method and apparatus with evaporative cooling
US5057593A (en) * 1990-06-11 1991-10-15 E. I. Du Pont De Nemours And Company Free radical copolymerization of ethylene and CO with acetone
WO2007134671A1 (en) * 2006-05-19 2007-11-29 Exxonmobil Chemical Patents Inc. A process for the production of polyethylene copolymers
US20100004407A1 (en) * 2006-05-19 2010-01-07 Ivo T Goossens Process for the Production of Polyethylene and Ethylene Copolymers
US8048971B2 (en) * 2006-05-19 2011-11-01 Exxonmobil Chemical Patents Inc. Process for the production of polyethylene and ethylene copolymers
CN101472950B (zh) * 2006-05-19 2013-06-05 埃克森美孚化学专利公司 聚乙烯共聚物的制备工艺
US8445606B2 (en) 2008-12-18 2013-05-21 Exxonmobil Chemical Patents Inc. High pressure polymerization process
US10358511B2 (en) 2009-12-22 2019-07-23 Exxonmobil Chemical Patents Inc. Separation vessels for use in polymerization processes and methods for cleaning same

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Publication number Publication date
NL7018035A (de) 1971-06-25
CH529797A (it) 1972-10-31
GB1282237A (en) 1972-07-19
FR2074055A5 (de) 1971-10-01
DE2063190A1 (de) 1971-09-02

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